Apparatus for the production of metal coatings



Jilly 1970 J. KERSCHGENS 3,520,

APPARATUS FOR THE PRODUCTION CF METAL COATINGS Filed June 23. 1966 5 Sheets-Sheet l July 14, 1970 J. KERSCHGENS 3, ,7

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TOHAMM K6 RSCHG-MS BY 4w MW United States Patent 3,520,792 APPARATUS FOR THE PRODUCTION OF METAL COATINGS Johann Kerschgens, Scharnstein 63, Austria Filed June 23, 1966, Ser. No. 559,845 Claims priority, application Austria, July 12, 1965, A 6,341/ 65 Int. (ll. C23b /76; BOllr 3/00 US. Cl. 2M224 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to apparatus for the production of metal coatings by electrodeposition.

It has been proposed to produce metal coatings by immersing an article to be coated into a bath of an electrolyte. When a plurality of coatings are to be applied in succession, the article must be immersed in different baths and must be cleaned between successive baths. An article having metallic surfaces must be provided with protecting layers, which are resistant to the electrolyte, in those areas in which a coating is not desired. An application of metal coatings by electrodeposition on parts which are assembled and in areas which are not readily accessible is virtually impossible or involves costs which are intolerab-ly high. Another difliculty is due to the fact that a person must have long years of experience until he can carry out electrodeposition operations of the kind mentioned above and can determine the thickness of the metal coating in accordance with individual requirements.

It is an object of the invention to provide apparatus of the kind mentioned above which is simple in structure and can easily be operated even for application of metal coatings to surfaces which are small and which may be diificult to reach, or to assembled parts. It is another ob ject so to design an apparatus of this kind that even linear or punctiform portions of metal parts can be provided with electrodeposited coatings. A further object is to provide apparatus which is designed so that it enables an application of coatings of diiferent metals.

All these requirements are fulfilled in an apparatus according to the invention, which is characterized by a housing, which is provided with a power supply circuit and forms a mounting for detachable electrolyte containers, which are adapted to be connected to said housing to form a manipulable unit, each of said containers has a contact terminal, which is adapted to be connected by a complementary contact of the housing to one pole of the DC. source when the container is mounted in the housing, and a liquid carrier, which protrudes from the container and is moistened by the electrolyte and electrically conductively connected to the contact terminal, the housing having another terminal which is connected to the second pole of the source of current and adapted to be connected to the workpiece to be coated. As the equipment is a manipulable unit, it can easily be handled. The metal coating is applied in a simple manner in that the workpiece is connected to the second pole of the source of current and the surface to be provided with the coating is wiped with the electrolyte carrier. Each housing has associated with it a plurality of electrolyte containers which contain different electrolytes for producing difierent metal coatings. It is sufiicient to exchange the container in order to change the apparatus to the production of a coating of a different metal. Electrolytes may be provided, as well as containers for such electrolytes, which enable the application of metal coatings of gold, silver, tin, zinc, brass, copper, chromium, nickel, and cadmium. Apparatus according to the invention may be used, e.g., for electrodepositing a coating of noble metal on parts to be soldered, in order to improve their conductivity, or :for repairs on nickelor chromium-plated parts, as well as for applying any electrodepositible metal coating to areas which are diificultly accessible.

With various coating metals, the quality of the resulting coating depends, inter alia, on the use of a certain voltage and a certain current density during electrodeposition. To maintain these conditions in the apparatus according to the invention, a voltage controller and an associated adjusting means may be provided in the housing. A check of the proper operation of the apparatus is enabled by at least one pilot lamp, which is included in the electrodeposition circuit and preferably mounted in the housing. This lamp may also serve as a series resistor for limiting the electrodeposition current and the operating voltage. In addition to the described means for controlling the voltage and current, which means comprise in most cases an element which protrudes from the housing and serves for adjusting the voltage controller, the housing may be provided with a plurality of complementary contacts, to which ditferent voltages are applied, whereas the contact terminal of each electrolyte container is in touch only with one complementary contact so that each electrolyte is automatically connected to the optimum voltage for electrodeposition. In one embodiment, the electrolyte containers may be provided with extensions, cams or the like, which are located in dependence on the content of the container and when the container is mounted in the housing said extensions, cams or the like cooperate with stops or the like to adjust the voltage controller to the nominal voltage which is required in each case.

With smaller apparatus, the power source may comprise batteries accommodated in the housing. With larger apparatus or Where high current densities are required, e.g., for chromium-plating, power sources may be used which are disposed outside the housing and comprise electric storage batteries or mains transformers succeeded by rectifiers.

Further details and preferred embodiments of the invention will become apparent from the following description of the accompanying drawings, in which the subject matter of the invention is illustrated by way of example.

FIG. 1 is an elevation showing a hand instrument,

FIG. 2 a view of the instrument of FIG. 1 with the housing cover removed,

FIG. 3 an elevation showing a smaller unit,

FIG. 4 a view partly in section showing a unit in the form of a pen and FIG. 5 an elevation showing a similar unit,

FIGS. 6, 7 and 8 illustrate various forms of the liquid carrier and of the contact terminals in a unit as shown in FIGS. 4 and 5,

FIG. 9 is a perspective view showing a case for the instrument of FIGS. 1 and 2 and FIG. 10 a sectional view taken on line X-X of FIG. 9 and showing the case.

FIGS. 11 and 12 are sectional views taken on line XI-XI of FIG. 12 and on line XII-XII of FIG. 11, respectively, and show an electrolyte container for units as shown in FIGS. 1 and 2 and in FIG. 3, respectively.

FIGS. 13 and 14 are partly sectional views showing further electrolyte containers and FIG. 15 is a diagrammatic elevation showing a further unit as used on an electrodeposition bath.

The unit shown in FIGS. 1 and 2 comprises a h using, which is composed of two shell sections 1, 2 and which has generally the form of a pistol comprising a grip 3. The two shell sections 1, 2 are connected by screws 4. An opening 5 for an insert is formed in the face of the housing. An electrolyte container 6 having an appropriately threaded portion 7 is adapted to be inserted into said opening. Detachable plug couplings similar to bayonet couplings may also be used for detachably mounting the electrolyte container.

Housing 1, 2 comprises mountings 8 for one or more dry cells 9. Leads extend from contacts 10 connected to the terminals of the dry cells to a multi-stage switch 11, which is operable by a toggle grip 12. That mounting 8 which is directed toward opening 5 comprises a fitting 13 for receiving the inner end portion of the electrolyte container. This fitting accommodates a complementary contact for supplying current to the electrolyte container.

Switch 12 enables a voltage control in that a plurality of batteries may be selectively connected in series or parallel or, with batteries 9 in the same basic circuit, switch 11 may have a cut-off position, in which it interrupts the circuit, another position, in which the poles of the battery are connected to the complementary contact and to a lead 14, which extends to the contact terminal, and a third position, in which switch 11 connects a series resistor in the last-mentioned circuit. Lead 14 may be provided with terminals for connection to a workpiece to be provided with a metal coating. These terminals will be described hereinafter. The series resistor may consist of a lamp 16, which is held in a socket 15 and protrudes through an opening in the housing.

Additional positions may be provided for switch 11. In one of these positions, it may disconnect the batteries and connect a lead to the complementary contact accommodated in part 13, which lead may be detachably connected by a plug to a receptacle of the housing, just as lead 14. In a further position, series resistor 16 may be connected in circuit with such further lead. These switch positions will be utilized if an extraneous power source is employed, e.g., an electric storage battery which is spaced from the housing, or a mains transformer succeded by rectifiers. One pole of this extraneous D.C. source is connected to the housing by the lead which corresponds to lead 14, and the second pole may be connected by a suitable lead directly to the workpiece. In any case, switch 11 may be replaced by different means for controlling voltage or current, e.g., by a continuously adjustable voltage controller. In any energizing position, a predetermined DC. voltage is applied to the complementary contact accommodated in part 13.

The unit shown in FIG. 3 is intended for use with the same electrolyte container 6 as the unit of FIGS. 1 and 2. To reduce the overall dimension, housing 17 consists in this case only of a mounting for dry cells. This mounting has an extension 18 with a fitting, corresponding to part 13, for receiving the end of the electrolyte container. The starting switch consists of a push button switch 19. There is also a lamp 16, which may be used as a pilot lamp or also as a series resistor.

Electrolyte containers for use with the units shown in FIGS. 1 to 3 are illustrated in FIGS. 11 to 13. In the embodiments shown by way of example, these electrolyte containers are basically hollow cylinders and have adjacent to one end an opening which can be closed by an insert 20. To enable a tight seal to be obtained with the insert 20, the same has preferably conical fitting surfaces 21 engaging the opening in container 6. The bottom part 22 of container 6 has a central enlarged portion, through which a metallic contact member 24 extends, which has at least one groove 25 to ensure liquid-tight fit. When container 6 is inserted in housing 1, 2, the

outside of contact member 24 engages the complementary contact accommodated in part 13. Container 6 has a collar 26. Between the opening and the collar, container 6 has further screw threads 27, with which a cover cap 28 may be engaged. Parts 6, 20 and 28 as well as preferably parts 1, 2, 17 and 18 and parts 8 and 13 are made by injection-molding from an electrically insulating synthetic resin which is resistant to acids and bases. The removal of cap 28 is facilitated by a knurled surface 29.

When insert 20 has been removed, container 6 may be filled with an electrolyte which contains a predetermined metal salt or a plurality of predetermined metal salts in predetermined proportions. It is recommended to provide the containers with indelible inscriptions, e.g., in the form of engravings or embossments, which indicate the nature of the electrolyte to be filled into the container and the nature of the metal to be deposited as a surface coating from this electrolyte. As to the nature of the electrolyte, it is sufficient in most cases to indicate whether the electrolyte contains cyanine or whether another acid or basic electrolyte is concerned.

A liquid carrier is mounted in insert 20. According to FIGS. 11 to 13 this liquid carrier consists of a Woven fabric pad 30 of acidand base-resisting material, preferably of synthetic resin fibers, such as polyvinylchloride fibers, or asbestos, glass wool, or the like. This liquid carrier 30 is held together by a metal band 31, which is conductively connected to a complementary contact 32, which consists of a substantially U-shaped metal strip. Liquid carrier 30 and metal band 31 are clamped between the ends of the limbs of the U-shaped strip. In the showing of FIGS. 11-13, part 32 may be inserted from above into insert 20 and is resiliently retained therein.

A screw 33 connects contact member 24 to a contact 34, which is also U-shaped and has limbs which are biased toward each other. Parts 31-34 are made from material which resists acids and bases, preferably from sheet nickel-chromium steel. Insert 20 with parts 3032 mounted thereon is inserted into container 6 so that the lower portion of part 32 enters between the limbs of part 34 and urges said limbs apart. The limbs of part 34 tend to return to their initial position and resiliently bear on part 32 to establish a good contact between contact member 24 and band 31 and further to the liquid carrier 30 when the same is impregnated. Parts 31, 32, 34 may have different cross-sections or may be made from material having different electrical conductivities so that these parts may be used as resistors for use with specific electrolytes.

As these conductors are heated when current flows therethrough, they may be used for preheating the electrolyte to a predetermined temperature desirable for the electrodeposition of metal from a respective electrolyte. Alternatively, resistance-heating elements may be pro vided for connection in the circuit by separate contacts and may be accommodated, e.g., in the container 6. Where relatively high temperatures are required for carrying out electrodeposition or where experience has shown that a given electrolyte is used only for a short time, it will sometimes be recommendable to provide adjacent to the liquid carrier a heating means which heats the liquid passing through the liquid carrier before it is discharged therefrom.

According to FIGS. 11 and 12, part 12 carries a basket 35, which is immersed in the electrolyte in container 6 when the insert is in position. This basket contains the metal to be deposited. For instance, it may contain pellets which consist of the metal to be deposited or of salts of the metal to be deposited and the electrolyte. According to FIG. 13, part 32 carries a concial pin 36, which serves to urge the limbs of contact member 34 apart during the fitting of insert 20 and which may consist of the metal to be deposited. The described provision of a supply of the metal to be deposited has the advantage that the electrolyte will be automatically replenished with the metal to be deposited so that one filling of the container will last longer than without such replenishing. To promote the decomposition, the replenishing material may be included in auxiliary circuits. Parts of the contacts in container 6 may also be made of the metal to be deposited.

A unit as shown in FIGS. 1, 2 and 11 to 13 may be held in a case as shown in FIGS. 9 and 10. This case has a base 37 and a covering hood 38 with a recess 39, which is adapted to receive a flexible carrying handle 40. The case has further a quick-action lock 41. The base is provided with a false bottom 42, which has a depression 43 conforming to the housing 1, 2 and which is further formed with mountings in the form of wells or apertures for receiving the containers 6 in a juxtaposed arrangement so that the containers may be held by collars 26 in wells 44, which may carry inscriptions which correspond to the inscriptions on the containers. Further apertures 45, 46 may be used as mountings for containers e.g., for cleaning or polishing agents. The case may also accommodate further containers or pans or the like, which are placed under the workpiece during electrodeposition and collect dripping electrolyte. In a modification of the structure which has been described, the case may be larger in size and may accommodate an electric storage battery or a mains transformer with succeeding dry rectifiers of the supply of power to the unit. The apparatus according to the invention is operated in most cases with voltages between 2 volts and 24 volts and currents up and above 2 amperes.

The apparatus which has been described thus far may be handled like a soldering gun. For particularly delicate work, to which electrodeposition methods were not adaptable before, units as shown in FIGS. 4 to 8 may be employed. These units comprise also a housing 48, which contains a battery 47 and to which a plurality of electrolyte containers may be successively connected so as to be readily detachable. Housing 48 and an electrolyte container attached to it form a unit which is similar to a pen. Housing 48 is provided with an on-off switch 50 and a pilot lamp 51. Container 49 contains a contact consisting of a U-shaped metal strip, which has limbs that are biased toward each other. Container 49 is closed by a detachably mounted cap 52, which is provided with a removable protecting cap 53. According to FIG. 4, a wicklike liquid carrier 54 extends outwardly through an opening 55 in the face of the cap 52 and is held between the limbs of a resilient complementary contact 56.

According to FIG. 6, a U-shaped complementary contact 57 is provided, which has a pin extension 58. Liquid carrier 54 is adjoined by a part 59 of felt or the like, which contains metal to be deposited, or salts of such metal, in a finely divided state. The felt may also form itself the liquid carrier protruding from the opening 55. According to FIG. 7, a pinlike liquid carrier 60 is provided, which may be designed, e.g., like the refill of a felt pencil known for painting or drawing, and is pressed into a threaded bushing 61, which is screwed into cap 52. A complementary contact 62 terminates in pin 60 and when the cap is mounted this contact 62 cooperates with contact 34. Instead of a pin 60., the liquid carrier may consi st of a brush made of acid-resisting fibers.

According to FIG. 8, a complementary contact 63 together with the suitably shaped opening 55 forms a mounting and guide for a porous ball 64, which constitutes the liquid carrier and which is rotatable like the ball of a ball point pen.

In FIGS. 4 and 5, a lead 65 or 66 is provided for connecting the power source to the workpiece to be coated with metal. Instead of a normal connection to terminals, lead 66 may be provided with a conducting surface and made from a flexible strand, which is shaped into a loop 67, as shown in FIG. 5. This loop is slipped around the hand which handles the pen. As this hand bears on the workpiece during the work, the latter is connected to the second pole of the source of current. Another possibility is illustrated on the right in FIG. 5. Cap 52 carries a circular series of outwardly protruding contact springs 68, which are electrically insulated from liquid carrier 54 and connected to the second pole of the source of current. When the workpiece is engaged with the liquid carrier, at least one of contact springs 68 will automatically contact the workpiece so that the circuit is closed. It would also be possible to provide directly beside the liquid carrier at protruding contact spring, which is electrically insulated from the liquid carrier and has a conducting end.

Apparatus as described in connection with FIGS. 4-8 may be used for extremely delicate work, e.g., for goldplating parts to be soldered in printed circuits, for the provision of electrodeposited inscriptions on metal plates, for providing noble metal coatings on engraved portions or for directly providing ornament similar to engravings on jewelry, etc.

The container shown in FIG. 14 is intended for electrodepositing operations in which a very hot electrolyte is required, or a very high current density, so that the electrolyte becomes very hot. In this case the container 6 is provided with an insert 69, which is adjoined by a small container 70, which extends into the interior of container 6 and communicates through inlet openings 71 with the interior of said container 6. The small container 70 carries a complementary contact 36 for cooperation with contact springs 34. A resistance heating element 72 extends from complementary contact 36 into the interior of a tube 73, which consists of glass having Very good heat-resisting properties. At one end, tube 73 is angled or provided with a T-shaped enlarged portion 74, as is shown. The enlarged portion 74 serves as a liquid carrier and has capillary outlet openings 75. Tube 73 is held in the insert by a heat-resisting seal 76, which is adapted to be clamped by a pressure member 77. During operation of the unit, the same is handled with liquid carrier 74 directed downwardly so that the electrolyte can emerge through openings 75. Only a small amount of liquid is preheated at a time in the small container 70 so that the electrolyte is quickly preheated. The heating to the desired end temperature is eifected within tube 73. To avoid an excessive temperature rise of the electrolyte, e.g., during hard chromium plating, where high current densities are required, a temperature feeler cooperating with a temperature measuring instrument mounted on the unit, as well as a cooling device, may be mounted adjacent to the liquid carrier. Electrically operated cooling devices may be used, particularly in the form of so-called refrigerating elements. A simple cooling means will be obtained if cold electrolyte is supplied directly to the liquid carrier or to the outlet region of the liquid carrier. This may be effected by means of a conduit 78, which is indicated in dotted lines in FIG. 14 and discharges adjacent to liquid carrier 74. From the interior of the container, or from a separate supply container, this conduit is supplied with cold electrolyte through a valve 79. The valve 79 is preferably operable by a handle which is mounted on the housing.

As is shown in FIG. 15, a modification comprises a housing 80 which is provided with instruments 81, 82, 83 for measuring the temperature of the electrolyte in the electrodeposition area and for measuring the operating voltage and current. Controllers for voltage and current will be additionally accommodated in the housing. Such unit is preferably operated from an extraneous power source, which may consists of a battery 84, as shown, or of a preferably variable transformer and succeeding rectifiers. A unit of the type described is intended particularly for industrial use. Apart from containers as described in connection with FIGS. 1 to 3 and 11 to 14, the housing terminals otherwise intended for the container may be connected to workpiece mountings 85 or similar terminals of an electrodeposition bath. Workpieces to be subjected to electrodeposition may be secured to the workpiece mountings 85 and may be immersed in an electrodeposition bath 87 in a tub S6. The second terminal of the power source 84 is then connected to a second terminal 88 of tub 86. In the latter application, housing 80 serves as a current and voltage controller and as a temperature supervising means for the electrodeposition bath 87, which may be used for electrodepositing a coating, e.g., on mass-produced articles. In a further modification, tub 86 forms instead of part 37 the base of a case as shown in FIGS. 9 and 10 and is downwardly removable from the case and held therein by quickaction connectors. The opposite pole consists of a bottom grid of a nickel-chromium alloy steel and is connected by a lead to a plug coupling, which is adapted to be connected to the current source.

The invention is not restricted to the various embodiments which have been described.

What is claimed is:

1. Apparatus for the production of a selected metal coating by electrodeposition, comprising (1) a housing shaped to be held in a hand;

(2) an electric power supply including a voltage controller carried by said housing and having two DC. output terminals;

(3) a control mounted in said housing and adapted to adjust the voltage controller;

(4) a selectable electrolyte container of insulating material,

(a) said container being interchangeably mounted in said housing;

(b) said selected container adapted to hold an electrolyte containing ions of the selected metal;

(c) said container having a contact terminal cooperating with one of said output terminals;

(d) a liquid carrier protruding from said container and arranged to be moistened by the electrolyte in the container;

(e) a metallic contact member within said container in circuit with said contact terminal thereof and comprising limbs biased toward each other; and

(f) a metallic conductor in contact with said liquid carrier and including a complementary contact element slidably and removably fitted between said limbs for placing the liquid carrier in circuit with said contact terminal;

(5) means for regulating the temperature of the electrolyte in the selected container; and

(6) means for electrically connecting the other one of said DC output terminals to a workpiece to be coated with the selected metal.

2. Apparatus as set forth in claim 1 wherein said metallic conductor comprises a substantially U-shaped metal strip having two limb ends clamping said liquid carrier between them.

3. Apparatus as set forth in claim 1 wherein said means for regulating the temperature of the electrolyte includes a non-insulated resistance heating element electrically connected to said power supply by said contact terminal and extending through the interior of the container.

4. Apparatus as set forth in claim 1 wherein said means for regulating the temperature of the electrolyte comprises a heating device provided adjacent said liquid carrier and operable to heat liquid flowing from said container to the liquid carrier for discharge thereby.

5. Apparatus as set forth in claim 4 in which said liquid carrier includes a heat-resisting tube having capillary outlet openings and also having an inlet opening disposed in said container.

6. Apparatus as set forth in claim 5 in which said heating device comprises a resistance heating element extending through the container and into said tube.

References Cited UNITED STATES PATENTS 800,791 10/1905 Bowden 204-271 828,814 8/1906 Cunningham 204-224 899,226 9/1908 Lutz 204-287 XR 1,552,591 9/1925 Batenburg 204-224 2,046,440 7/ 1936 Adey 204-224 XR 2,491,910 12/1949 Schinske 204-224 XR 2,798,849 7/ 1957 Lindsay 204-224 2,961,395 11/1960 Icxi 204224 3,294,664 12/1966 Franklin 204-224 3,326,793 6/1967 Lennon 204-224 3,346,477 10/ 1967 Wolfer 204-224 FOREIGN PATENTS 976,322 3/1951 France.

JOHN H. MACK, Primary Examiner D. R. VALENTINE, Assistant Examiner US. Cl. X.R. 

